[llvm] r217106 - [asan] fix debug info produced for asan-coverage=2

Thu Sep 4 01:45:09 PDT 2014

Alloca-s in the entry basic block quite often don't have any debug
location. Would you consider this worth fixing?
There are other instructions that never or almost never get debug
location, ex: branch instructions.

On Thu, Sep 4, 2014 at 4:53 AM, Kostya Serebryany <kcc at google.com> wrote:
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> On Wed, Sep 3, 2014 at 4:47 PM, David Blaikie <dblaikie at gmail.com> wrote:
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>> On Wed, Sep 3, 2014 at 4:24 PM, Kostya Serebryany <kcc at google.com> wrote:
>>>
>>> Author: kcc
>>> Date: Wed Sep  3 18:24:18 2014
>>> New Revision: 217106
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=217106&view=rev
>>> Log:
>>> [asan] fix debug info produced for asan-coverage=2
>>>
>>> Added:
>>>     llvm/trunk/test/Instrumentation/AddressSanitizer/coverage2-dbg.ll
>>> Modified:
>>>     llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
>>>
>>> Modified: llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp?rev=217106&r1=217105&r2=217106&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
>>> (original)
>>> +++ llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp Wed
>>> Sep  3 18:24:18 2014
>>> @@ -1321,7 +1321,9 @@ void AddressSanitizer::InjectCoverageAtB
>>>        break;
>>>    }
>>>
>>> -  DebugLoc EntryLoc = IP->getDebugLoc().getFnDebugLoc(*C);
>>> +  DebugLoc EntryLoc = &BB == &F.getEntryBlock()
>>> +                          ? IP->getDebugLoc().getFnDebugLoc(*C)
>>> +                          : IP->getDebugLoc();
>>
>>
>> What's the need for the conditional/special case? (is there a reason
>> IP->getDebugLoc() doesn't work in the general case?)
>
>
> There was a case which eugenis@ has hit on Android and for which there is a
> test:
> llvm/trunk/test/Instrumentation/AddressSanitizer/coverage-dbg.ll
> We want the first basic block to have debug info of the opening curly brace
> of the function.
>
> Evgenyi, am I right?
>
>>
>>
>>>
>>>    IRBuilder<> IRB(IP);
>>>    IRB.SetCurrentDebugLocation(EntryLoc);
>>>    Type *Int8Ty = IRB.getInt8Ty();
>>>
>>> Added: llvm/trunk/test/Instrumentation/AddressSanitizer/coverage2-dbg.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Instrumentation/AddressSanitizer/coverage2-dbg.ll?rev=217106&view=auto
>>>
>>> ==============================================================================
>>> --- llvm/trunk/test/Instrumentation/AddressSanitizer/coverage2-dbg.ll
>>> (added)
>>> +++ llvm/trunk/test/Instrumentation/AddressSanitizer/coverage2-dbg.ll Wed
>>> Sep  3 18:24:18 2014
>>> @@ -0,0 +1,75 @@
>>> +; Test that coverage instrumentation does not lose debug location.
>>> +
>>> +; RUN: opt < %s -asan -asan-module -asan-coverage=2 -S | FileCheck %s
>>> +
>>> +; C++ source:
>>> +; 1: void foo(int *a) {
>>> +; 2:     if (a)
>>> +; 3:         *a = 0;
>>> +; 4: }
>>> +; clang++ if.cc -O3 -g -S -emit-llvm
>>> +; and add sanitize_address to @_Z3fooPi
>>
>>
>> Can this attribute be added in the original source? Or is it not utterable
>> at the moment? (will/should it be? or is this by design?)
>>
>>>
>>> +
>>> +
>>> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>> +target triple = "x86_64-unknown-linux-gnu"
>>> +
>>> +; Check that __sanitizer_cov call has !dgb pointing to the beginning
>>> +; of appropriate basic blocks.
>>> +; CHECK-LABEL:_Z3fooPi
>>> +; CHECK: call void @__sanitizer_cov(), !dbg [[A:!.*]]
>>> +; CHECK: call void @__sanitizer_cov(), !dbg [[B:!.*]]
>>> +; CHECK: call void @__sanitizer_cov(), !dbg [[C:!.*]]
>>> +; CHECK: ret void
>>> +; CHECK: [[A]] = metadata !{i32 1, i32 0, metadata !{{.*}}, null}
>>> +; CHECK: [[B]] = metadata !{i32 3, i32 5, metadata !{{.*}}, null}
>>> +; CHECK: [[C]] = metadata !{i32 4, i32 1, metadata !{{.*}}, null}
>>> +
>>> +define void @_Z3fooPi(i32* %a) #0 {
>>> +entry:
>>> +  tail call void @llvm.dbg.value(metadata !{i32* %a}, i64 0, metadata
>>> !11), !dbg !15
>>> +  %tobool = icmp eq i32* %a, null, !dbg !16
>>> +  br i1 %tobool, label %if.end, label %if.then, !dbg !16
>>> +
>>> +if.then:                                          ; preds = %entry
>>> +  store i32 0, i32* %a, align 4, !dbg !18, !tbaa !19
>>> +  br label %if.end, !dbg !18
>>> +
>>> +if.end:                                           ; preds = %entry,
>>> %if.then
>>> +  ret void, !dbg !23
>>> +}
>>> +
>>> +; Function Attrs: nounwind readnone
>>> +declare void @llvm.dbg.value(metadata, i64, metadata) #1
>>> +
>>> +attributes #0 = { nounwind uwtable "less-precise-fpmad"="false"
>>> "no-frame-pointer-elim"="false" "no-infs-fp-math"="false"
>>> "no-nans-fp-math"="false" "stack-protector-buffer-size"="8"
>>> "unsafe-fp-math"="false" "use-soft-float"="false" sanitize_address}
>>> +attributes #1 = { nounwind readnone }
>>> +
>>> +!llvm.dbg.cu = !{!0}
>>> +!llvm.module.flags = !{!12, !13}
>>> +!llvm.ident = !{!14}
>>> +
>>> +!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version
>>> 3.6.0 (217079)", i1 true, metadata !"", i32 0, metadata !2, metadata !2,
>>> metadata !3, metadata !2, metadata !2, metadata !"", i32 1} ; [
>>> DW_TAG_compile_unit ] [FOO/if.cc] [DW_LANG_C_plus_plus]
>>> +!1 = metadata !{metadata !"if.cc", metadata !"FOO"}
>>> +!2 = metadata !{}
>>> +!3 = metadata !{metadata !4}
>>> +!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"foo",
>>> metadata !"foo", metadata !"_Z3fooPi", i32 1, metadata !6, i1 false, i1
>>> true, i32 0, i32 0, null, i32 256, i1 true, void (i32*)* @_Z3fooPi, null,
>>> null, metadata !10, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [foo]
>>> +!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ]
>>> [FOO/if.cc]
>>> +!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64
>>> 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [
>>> DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
>>> +!7 = metadata !{null, metadata !8}
>>> +!8 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64
>>> 64, i64 0, i32 0, metadata !9} ; [ DW_TAG_pointer_type ] [line 0, size 64,
>>> align 64, offset 0] [from int]
>>> +!9 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32,
>>> i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32,
>>> align 32, offset 0, enc DW_ATE_signed]
>>> +!10 = metadata !{metadata !11}
>>> +!11 = metadata !{i32 786689, metadata !4, metadata !"a", metadata !5,
>>> i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [a] [line
>>> 1]
>>> +!12 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
>>> +!13 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
>>> +!14 = metadata !{metadata !"clang version 3.6.0 (217079)"}
>>> +!15 = metadata !{i32 1, i32 15, metadata !4, null}
>>> +!16 = metadata !{i32 2, i32 7, metadata !17, null}
>>> +!17 = metadata !{i32 786443, metadata !1, metadata !4, i32 2, i32 7, i32
>>> 0} ; [ DW_TAG_lexical_block ] [FOO/if.cc]
>>> +!18 = metadata !{i32 3, i32 5, metadata !17, null}
>>> +!19 = metadata !{metadata !20, metadata !20, i64 0}
>>> +!20 = metadata !{metadata !"int", metadata !21, i64 0}
>>> +!21 = metadata !{metadata !"omnipotent char", metadata !22, i64 0}
>>> +!22 = metadata !{metadata !"Simple C/C++ TBAA"}
>>> +!23 = metadata !{i32 4, i32 1, metadata !4, null}
>>>
>>>
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